The new tier is $5 cheaper than the regular plan, costing just $10 per month in the US. Keep in mind the whole point of HBO from the get-go was an ad-free content experience, so many have wondered how the network plans to suddenly start incorporating commercials. Executives are promising "an elegant, tasteful ad experience that is respectful of great storytelling".
Those who choose to subscribe to the cheaper tier will not only get HBO Max's new "tasteful" ads but also fewer premium features. Video streaming quality will be limited to 1080p, reserving 4K streaming for the regular plan. Also, some titles will not be available for offline viewing, and even same-day movie premieres will be limited to subscribers of the regular plan.
Ad-supported plan subscribers will eventually be able to watch these titles; they'll just need to wait months after their theatrical release windows end in the US. Those on the ad-supported plan will have access to HBO Max Originals, however.